The present invention relates to a control device that performs cruise control for an automotive vehicle so as to allow a set target vehicle speed to coincide with an actual vehicle speed and a control method for the same.
Japanese Patent Laid-open No. Hei 10-53046 discloses a technique that is concerned with a resume operation. Specifically, after an auto cruise control is temporarily interrupted by a driver's operating a brake or the like to reduce a vehicle speed of a host vehicle, the driver operates a resume switch to restore the vehicle speed to a target vehicle speed or a stored vehicle speed immediately before the auto cruise control has been interrupted. The technique disclosed in Japanese Patent Laid-open No. Hei 10-53046 does not use the stored vehicle speed as a target vehicle speed for vehicle speed feedback control in the resume mode. Rather, it sets an actual vehicle speed developing when the resume operation is started as the target vehicle speed for the vehicle speed feedback control, thereby bringing the target vehicle speed gradually to the stored vehicle speed.
Japanese Patent Laid-open No. Hei 11-34695 refers to acceleration feedback control during acceleration of a vehicle. It is intended for improving the response of a throttle.
According to Japanese Patent Laid-open No. Hei 10-53046, if a vehicle speed feedback gain is set appropriately so as to allow the actual vehicle speed to properly follow the target vehicle speed, it is possible to minimize a vehicle speed deviation at all times. This is effective in preventing acceleration from becoming excessively large. If the feedback gain is made inappropriate as caused by a road gradient, a wind velocity, or other disturbance, however, the actual vehicle speed becomes unable to follow the target vehicle speed, thus making large the vehicle speed deviation. In such a case, a vehicle speed feedback control device acts to make small the vehicle speed deviation. This presents a problem, in which a vehicle acceleration becomes excessively large as a result of an engine torque changing by a large margin.
Japanese Patent Laid-open No. Hei 11-34695 refers to the acceleration feedback control during the acceleration of a vehicle. It is intended for improving throttle response, not concerned with driver's comfort or vehicle stability.
Accordingly, there is a challenge that must be addressed, in which excessive acceleration and deceleration should be prevented under all possible conditions.